During the last decade, evolutionary methods such as genetic algorithms have been used extensively for the optimal design and operation of water distribution systems. More recently, ant colony ...optimization algorithms (ACOAs), which are evolutionary methods based on the foraging behavior of ants, have been successfully applied to a number of benchmark combinatorial optimization problems. In this paper, a formulation is developed which enables ACOAs to be used for the optimal design of water distribution systems. This formulation is applied to two benchmark water distribution system optimization problems and the results are compared with those obtained using genetic algorithms (GAs). The findings of this study indicate that ACOAs are an attractive alternative to GAs for the optimal design of water distribution systems, as they outperformed GAs for the two case studies considered both in terms of computational efficiency and their ability to find near global optimal solutions.
Objectives
To use multi-parametric magnetic resonance imaging (MRI) to test the hypothesis that hypertensives would have higher retrograde venous blood flow (RVBF) in the internal jugular veins (IJV) ...vs. normotensives, and that this would inversely correlate with arterial inflow and gray matter, white matter, and cerebrospinal fluid volumes.
Methods
Following local institutional review board approval and written consent, a prospective observational 3-T MRI study of 42 hypertensive patients (53 ± 2 years, BMI 28.2 ± 0.6 kg/m
2
, ambulatory daytime systolic BP 148 ± 2 mmHg, ambulatory daytime diastolic BP 101 ± 2 mmHg) and 35 normotensive patients (48 ± 2 years, BMI 25.2 ± 0.8 kg/m
2
, ambulatory daytime systolic BP 119 ± 3 mmHg, ambulatory daytime diastolic BP 90 ± 2 mmHg) was performed. Phase contrast imaging calculated percentage retrograde venous blood flow (%RVBF), brain segmentation estimated regional brain volumes from 3D T1-weighted images, and pseudo-continuous arterial spin labeling measured regional cerebral blood perfusion. Statistical analysis included two-sample equal variance Student’s
T
tests, two-way analysis of variance with Tukey’s post hoc correction, and permutation-based two-group general linear modeling (
p
< 0.05).
Results
In the left IJV, %RVBF was higher in hypertensives (6.1 ± 1.5%) vs. normotensives (1.1 ± 0.3%,
p
= 0.003). In hypertensives, there was an inverse relationship of %RVBF (permutation-based general linear modeling) to cerebral blood flow in several brain regions, including the left occipital pole and the cerebellar vermis (
p
< 0.01). Percentage retrograde flow in the left IJV correlated inversely with the total matter volume (gray plus white matter volume) in hypertensives (
r
= − 0.49,
p
= 0.004).
Conclusion
RVBF in the left IJV is greater in hypertensives vs. normotensives and is linked to regional hypoperfusion and brain total matter volume.
Key Points
• Hypertensive humans have higher retrograde cerebral venous blood flow, associated with regional brain hypoperfusion and lower tissue volume, compared with controls.
• Cerebral retrograde venous blood flow may add further stress to already hypoperfused tissue in hypertensive patients.
• The amount of retrograde venous blood flow in hypertensive patients may predict which patients might be at higher risk of developing cerebral pathologies.
Soybean, Glycine max (L.) Merr., is planted during 3.5–4 mo across the Mid-South United States. Currently, no information exists regarding the effects of planting date on soybean yield loss from ...early season defoliation. In 2015 and 2016, to evaluate the effects of planting date on yield loss from defoliation, soybean were planted in field plots 2 wk apart from early April to mid-June, for a total of six planting dates. Each planting date included a nondefoliated control and a 100% defoliation treatment where leaves were manually excised at the V4 growth stage. Mean yield loss from defoliation varied across planting dates, with mid-April plantings having the least amount yield reduction, 573 kg/ha, and early-June plantings having the greatest yield reduction, 904 kg/ha. Percent yield reduction from defoliation increased as planting was delayed, suggesting that defoliation thresholds might need adjustment based on planting date and yield potential. However, more research is needed at lower levels of defoliation to accurately delineate such thresholds.
Introduction
Although antiviral prophylaxis is effective in preventing early cytomegalovirus (CMV) reactivation following liver transplantation (OLT), it predisposes patients to late CMV after ...prophylaxis has ceased. QuantiFERON–CMV (QFN‐CMV, Qiagen, The Netherlands) measures an individual's viral‐specific immune response.
Methods
Fifty‐nine OLT recipients were prospectively monitored post‐OLT in an observational cohort study. QFN‐CMV was performed at regular time‐points. An absolute QFN‐CMV <0.1 IU/mL was considered non‐reactive.
Results
50/59 (84.7%) had a reactive QFN‐CMV by M6. 38/59 (64.4%) had antiviral prophylaxis or treatment before M6, with 31/38 (81.6%) developing a reactive QFN‐CMV by 6 months. Over 90% already had a reactive result as early as 3 months post transplant, 3 patients (5.08%) developed late CMV between 6‐12 months (median 251 days)—all had a non‐reactive M6 QFN‐CMV. And 2/3 experienced CMV disease. Non‐reactive M6 QFN‐CMV was significantly associated with late CMV (OR = 54.4, PPV = 0.33, NPV = 1.00, P = .003).
Conclusion
Although only 5% of recipients developed late CMV, 2/3 suffered CMV disease. M6 QFN‐CMV has an excellent NPV for late CMV, suggesting patients who exhibit a robust ex vivo immune response at M6 can safely cease CMV monitoring. Furthermore, >90% already express viral‐specific immunity as early as 3 months. Conceivably, antiviral prophylaxis could be discontinued early in these patients.
Objective To determine the incidence and risk factors for readmission to the intensive care unit (ICU) among preterm infants who required mechanical ventilation at birth. Study design We studied ...preterm newborns (birth weight 500-1250 g) who required mechanical ventilation at birth and were enrolled in a multicenter trial of inhaled nitric oxide therapy. Patients were assessed up to 4.5 years of age via annual in-person evaluations and structured telephone interviews. Univariate and multivariable analyses of baseline and birth hospitalization predictors of ICU readmission were performed. Results Of 512 subjects providing follow-up data, 58% were readmitted to the hospital (51% of these had multiple readmissions, averaging 3.9 readmissions per subject), 19% were readmitted to an ICU, and 12% required additional mechanical ventilation support. In univariate analyses, ICU readmission was more common among male subjects (OR 2.01; 95% CI 1.27-3.18), infants with grade 3-4 intracranial hemorrhage (OR 2.13; 95% CI 1.23-3.69), increasing duration of birth hospitalization (OR 1.01 per day; 95% CI 1.00-1.02), and prolonged oxygen therapy (OR 1.01 per day; 95% CI 1.00-1.01). In the first year after birth hospitalization, children readmitted to an ICU incurred greater health care costs (median $69 700 vs $30 200 for subjects admitted to the ward and $9600 for subjects never admitted). Conclusions Small preterm infants who were mechanically ventilated at birth have substantial risk for readmission to an ICU and late mechanical ventilation, require extensive health care resources, and incur high treatment costs.
PDF
